Tempered water safety showers are used in a wide range of industries in which workers are exposed to toxic and hazardous chemicals that can cause serious tissue damage upon contact. Occupational Safety and Health Administration regulations require the availability of emergency safety showers for use as a form of first aid treatment. ANSI standard Z358.1 requires that these showers can deliver at least 20 gallons of water per minute for a time period of 15 minutes over the body of a person who has been exposed to an aggressive chemical.
It has been found that there are problems relating to a 15-minute sustained time in cold water for any individual, and particularly for a person who is already in or subject to traumatic shock. The body quickly begins to react to the cold by shivering in order to fight off cold and generate body heat. The sustained flow of cold water increases the loss of body heat beyond the body's ability to maintain adequate temperature levels and further stimulates the metabolic rate to compensate. Ultimately, the user enters thermal shock and/or refuses to remain in the shower for the time required for adequate treatment. Moreover, use of cold water discourages the effective, maximum use of the safety shower temperature for the 15-minute period which is required by the ANSI standard. Users tend to leave the shower much earlier when being deluged with cold water.
Tempered water blending systems usually provide drench water at almost 85.degree. F-90.degree. F., and at the temperature levels sufficient to provide relief to the affected tissue while allowing the user to remain immersed for the required treatment period. Most systems use basically mechanical, temperature-control devices which respond sluggishly to temperature changes with a pressure drop across the system of from about 30 to 40 psi. Even later-model electro-mechanical systems that allow existing plant hot and cold water supplies to be accurately and safely blended to a preset, non-adjustable, safe, utilization temperature leave something to be desired as far as responsiveness and fail-safe operation is concerned. Such systems are readily available in industrial safety catalogs. Because of this and other desires for tempered water safety showers, there exists a need for the development of a tempered water emergency shower that is simpler, more economical and safer to use.